全文获取类型
收费全文 | 4250篇 |
免费 | 330篇 |
国内免费 | 1篇 |
出版年
2022年 | 27篇 |
2021年 | 62篇 |
2020年 | 40篇 |
2019年 | 54篇 |
2018年 | 51篇 |
2017年 | 41篇 |
2016年 | 112篇 |
2015年 | 147篇 |
2014年 | 208篇 |
2013年 | 233篇 |
2012年 | 292篇 |
2011年 | 289篇 |
2010年 | 194篇 |
2009年 | 167篇 |
2008年 | 253篇 |
2007年 | 204篇 |
2006年 | 207篇 |
2005年 | 179篇 |
2004年 | 176篇 |
2003年 | 162篇 |
2002年 | 171篇 |
2001年 | 74篇 |
2000年 | 78篇 |
1999年 | 66篇 |
1998年 | 48篇 |
1997年 | 49篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 32篇 |
1993年 | 28篇 |
1992年 | 42篇 |
1991年 | 38篇 |
1990年 | 30篇 |
1989年 | 33篇 |
1988年 | 23篇 |
1987年 | 25篇 |
1986年 | 33篇 |
1985年 | 25篇 |
1984年 | 28篇 |
1979年 | 31篇 |
1978年 | 20篇 |
1977年 | 23篇 |
1976年 | 18篇 |
1975年 | 25篇 |
1974年 | 20篇 |
1973年 | 32篇 |
1972年 | 22篇 |
1971年 | 25篇 |
1970年 | 30篇 |
1967年 | 22篇 |
排序方式: 共有4581条查询结果,搜索用时 15 毫秒
11.
12.
Lars Svennerholm Pam Fredman Birgitta Jungbjer Jan-Eric Månsson Britt-Marie Rynmark Kerstin Boström Bengt Hagberg Lars Norén Pirkko Santavuori 《Journal of neurochemistry》1987,49(6):1772-1783
Lipid composition was studied on cerebral tissue from nine children who had died of a progressive encephalopathy called the infantile form of neuronal ceroid lipofuscinosis (INCL) or polyunsaturated fatty acid lipidosis (PFAL). In the terminal stage of the disease, the concentrations of all lipid classes were found to be significantly reduced in the cerebral and cerebellar cortex and white matter. The concentration of gangliosides of the cerebral cortex was 15% and that of cerebrosides (galactosylceramide) in white matter 0.2-5% of the normal values for the children's ages. The reduction of gangliosides mainly affected those of the gangliotetraose series, particularly GD1a. The fatty acids of the linolenic acid series were strongly reduced in ethanolamine and serine phosphoglycerides. A very large increase up to 100-fold of oligoglycosphingolipids of the globo series and two fucose-containing lipids of the neolacto series was found in the forebrain of the three advanced cases examined. The brain tissue also contained very high concentrations of mono-, di-, and trisialogangliosides of the lacto and neolacto series, gangliosides with type 1 chain dominating. The structures of the gangliosides were tentatively identified by gas chromatography-mass spectrometry and monoclonal antibodies with carefully determined epitope specificity. The gangliosides and neutral glycosphingolipids had very similar fatty acid composition, consisting of about 40% stearic acid and 40% C24-acids. 相似文献
13.
Solid-phase synthesis of oligoribonucleotides using 9-fluorenylmethoxycarbonyl (Fmoc) for 5''-hydroxyl protection. 总被引:7,自引:6,他引:1
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Efficient solid-phase synthesis of a series of oligoribonucleotides of up to 20 residues is described that utilises the 9-fluorenylmethoxycarbonyl group (Fmoc) for 5'-protection and 4-methoxytetrahydropyran-4-yl (Mthp) for 2'-protection of ribonucleotide monomers and a phosphoramidite coupling procedure. The Fmoc group is removed after each coupling step by treatment with 0.1M DBU in acetonitrile. Oligoribonucleotides are isolated in 2'-protected form in good yield and shown to be readily and efficiently deprotected by mild acidic treatment. 相似文献
14.
The distribution of the number of copies of P and I transposable elements per genome was investigated by in situ hybridization for a large set of Drosophila melanogaster strains. These included the P, Q and M types of the P-M system of hybrid dysgenesis. P element copy number varied widely (range 5–59). P and Q strains had around 40 copies whereas M strains generally had lower numbers (between 5 and 35) with one extreme value (52). The copy number of I elements appeared to be precisely regulated, as no strains were found outside the 15±5 range. The number of copies of the two families were independent. An excess of P copies on the X chromosome compared with the autosomes was found for the P and Q strains, but not for M strains. Among X-inserted P sites, a very high frequency of occupation was found at the tip of the X chromosome (cytological site 1A), especially for P and Q strains. The possible regulatory role in the P-M system of X-inserted P sites is discussed. 相似文献
15.
16.
Michèle Ramsay Stephen T. Reeders Peter D. Thomson Lawrence S. Milner L. Lazarou Thomas M. Barratt Adrian Yau Ordan J. Lehmann Trefor Jenkins 《Human genetics》1988,79(1):73-75
Summary The autosomal dominant form of polycystic kidney disease (ADPKD) has been linked to the -globin gene locus on 16p. Linkage studies between the autosomal recessive type (ARPKD) and the 3 HVR of the -globin gene cluster showed that the ARPKD and ADPKD are not allelic. 相似文献
17.
A serum free medium was developed, that could be used for the large scale propagation of various cell lines in bioreactors. The medium is based on a 1:1 mixture of Iscove's Modified Dulbecco's Medium and Ham's Medium F12, supplemented with transferrin, insulin and a BSA/oleic acid complex. Several myelomas, hybridomas derived from different myelomas and spleen cells, and other lymphoid and non-lymphoid cell lines were cultivated at growth rates comparable to those observed using serum-supplemented media. There was furthermore no reduction in the formation of products such as monoclonal antibodies or recombinant human interleukin-2.Abbreviations Ag8
Mouse myeloma cell line P3-X63-Ag8.653
- BME
Basal Medium Eagle
- BSA
Bovine Serum Albumin
- DMEM
Dulbecco's Modified Eagle's Medium
- EDTA
Ethylenediaminete-traacetic Acid
- e-PC
Phosphatidyl choline from egg yolk
- FCS
Fetal Calf Serum
- FGF
Fibroblast Growth Factor
- GHL
Glycyl-histidyl-lysine
- HDL
High Density Lipoprotein
- HPL
Human Plasma Lipid
- IF
1:1 mixture of IMDM and Ham's F12
- IMDM
Iscove's Modified Dulbecco's medium
- LDL
Low Density Lipoprotein
- NS1
Mouse myeloma cell line NSI-1-Ag4-1
- PBS
Phosphate Buffered Saline
- s-PC
Phosphatidylcholine from soy beans
- s-PE
Phosphatidylethanolamine from soy beans
- s-lecithin
lecithin from soy beans 相似文献
18.
S. O'Rahilly P. Patel O. J. Lehmann A. Tybjaerg-Hansen J. Nerup R. C. Turner J. S. Wainscoat 《Human genetics》1992,89(2):207-212
Summary Members of three families with maturity onset diabetes of youth (MODY) and seven with common type 2 diabetes were typed for six DNA markers (H-RAS, INS, HBBC, PTH, CALC1, CAT) on the short arm of chromosome 11. Using conventional pairwise linkage analysis, close linkage in the MODY families was excluded for all six markers. By multipoint analysis and a genetic map of the short arm of chromosome 11, MODY was excluded from a region of at least 35 and up to 60 centiMorgans (cM) on the short arm of chromosome 11. Multipoint analysis in the type 2 families also excludes linkage to the INS, H-RAS region of at least 3 and up to 30 cM. This study using multipoint linkage analysis in non-insulin dependent diabetes provides strong evidence against a role for mutations in or around the insulin gene in the causation of MODY or type 2 diabetes in the families studied. 相似文献
19.
Replication of bovine papillomavirus vectors in murine cells 总被引:2,自引:0,他引:2
Margareta Waldenstrm Kerstin Schenstrm Kerstin Sollerbrant Lennart Hansson 《Gene》1992,120(2):175-181
20.
Oskar organizes the germ plasm and directs localization of the posterior determinant nanos 总被引:33,自引:0,他引:33
Oskar is one of seven Drosophila maternal-effect genes that are necessary for germline and abdomen formation. We have cloned oskar and show that oskar RNA is localized to the posterior pole of the oocyte when germ plasm forms. This polar distribution of oskar RNA is established during oogenesis in three phases: accumulation in the oocyte, transport toward the posterior, and finally maintenance at the posterior pole of the oocyte. The colocalization of oskar and nanos in wild-type and bicaudal embryos suggests that oskar directs localization of the posterior determinant nanos. We propose that the pole plasm is assembled stepwise and that continued interaction among its components is required for germ cell determination. 相似文献